Screen sharing through sockets - vb.net

Question

I'm making my first screen sharing application in VB.NET using sockets to establish the connections.
This is the client side receiving screen images from the server (they are both running in a thread):
Private Sub startscreen()
Using imgstream As NetworkStream = imgclient.GetStream()
Using ms As New MemoryStream
Dim read As Double
Do
If (imgstream.DataAvailable) Then
read = 0
ms.Seek(0, SeekOrigin.Begin)
While imgclient.Available
Dim buffer(imgclient.Available - 1) As Byte
imgstream.Read(buffer, 0, buffer.Length)
ms.Write(buffer, 0, buffer.Length)
read += buffer.Length
End While
Me.Text = "Frame bytes read: " & read
PictureBox1.Image = Image.FromStream(ms)
ms.Flush()
End If
Thread.Sleep(34) 'about 30 FPS
Loop
End Using
End Using
End Sub
And this is the server side:
Private Sub screen()
Using imgstream As NetworkStream = imgclient.GetStream()
Using ms As New MemoryStream
Do
Thread.Sleep(34) 'about 30 FPS
ms.Seek(0, SeekOrigin.Begin)
Using img = ScreenCap()
img.Save(ms, Imaging.ImageFormat.Jpeg)
End Using
ms.WriteTo(imgstream)
Loop
End Using
End Using
End Sub
Public Function ScreenCap() As Image
Dim screenSize As Size = New Size(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
Dim screenGrab As New Bitmap(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height) ', Imaging.PixelFormat.Format16bppRgb555)
Dim g As Graphics = Graphics.FromImage(screenGrab)
g.CopyFromScreen(New Point(0, 0), New Point(0, 0), screenSize)
g.Dispose()
Return screenGrab
End Function
The main problem is when I call the "Image.FromStream(ms)" function, it sometimes works and others doesn't depending on how many milliseconds I set the thread to wait. Tested on 2 different computers in my LAN, on around 1 second it seems OK but always with a high CPU-Network usage. If I set, as the example says around 34 milliseconds to get all more "LIVE", that function throw an exception because of the MemoryStream. How can I speed it up? Is there any smarter way I'm missing right now? I've also tried putting a delimiter byte (like a char = "*") at the and of the MemoryStream and then send it to the client who read one byte at a time until it found a char equal to the delimiter. But it turned out to be a bad solution because a single byte of the image could represent the delimiter if converted to char. Another question I have is: How can I change the image quality and the color depth? Is it a good approach using what the comment says: "Imaging.PixelFormat.Format16bppRgb555"
Thank you!